Means for introducing agents into a surrounding liquid or gas are known. For instance, spray canisters connected to electric timers may be used to eject a scented gas or insect repellant into the air of a room at regular intervals. Also, perforated containers filled with chlorine crystals or tablets may be placed in the water of swimming pools to allow chlorine to seep into the surrounding water by the action of water passing through the perforated container.
In instances where it is desirable to introduce an agent into a gas or liquid, it is often also desirable to control the amount of agent being introduced. However in systems where the gas or liquid is flowing at random intervals, it can be especially difficult to control the degree to which an agent is introduced into the system. In such cases, it is desirable to have a system capable of responding to the random flow of the gas or liquid.
Systems which react directly to the random flow of a liquid or gas are known. A common example of such a system is the disinfectant dispenser sometimes used in household toilet tanks. This system incorporates a float valve which reacts to changes in the water level of the tank and dispenses a dose of disinfectant accordingly. A more sophisticated system is the Apparatus for Purifying Water described by Polley in U.S. Pat. No. 4,059,522. This system incorporates a Venturi tube in a primary water flow path to create a pressure differential and force a small portion of the water through a by-pass leading to an iodine saturation container. Once permitted to be saturated with iodine, the water is returned to the primary water line to purify the water supply.
Both systems described above use the pressure of randomly flowing water to control the introduction of agents into the water supply. The present invention is designed to provide a system that responds to changes in temperature in the random flow of a liquid or gas to control the introduction of agents into the liquid or gas supply.
One particular use for such a system lies in the field of water treatment. One of the problems associated with the treatment of domestic or institutional water systems is the relatively intermittent nature of the flow of water in such systems and the resultant bacterial buildup that can occur. In domestic or institutional water systems, bodies of water are stored in containers or tanks where the water may be drawn off from time to time. Makeup water is added to the container or tank when an equal amount of water is drawn off. Often the water that is drawn off must first pass through a filter element. Typically such filter elements are immersed in the container or tank itself. The containers or tanks are normally located in the interior of a building where the temperature will normally be at room temperature in the region of 20.degree. to 22.degree. C. At these temperatures, and with the water essentially motionless for varying lengths of time, bacteria within the water tend to settle on the filter and grow relatively actively. This can lead to rapid contamination of the filter and create health risks.
The present invention can be used in this circumstance to provide a system to treat the water standing in the container or tank with iodine following each time a fresh flow of water enters the system. When the iodine-treated water passes through the filter, the iodine remains on the filter and kills any bacteria that may exist.